Current radiofrequency ablation (“RF”) devices are constructed in a variety of configurations to target specific maladies and to provide for specific treatment protocols. In particular, many RF ablation devices have one or more treatment regions in which multiple treatment electrodes are disposed and are torqueable, or otherwise manipulatable, into a variety of different geometric configurations to treat particular cardiovascular tissues. For example, treatment electrodes may be coupled to an array or a carrier assembly manipulatable to define substantially linear, helical, and circular configurations depending on the desired treatment to be performed. In such configurations, each adjacent electrode may be spaced a distance away, whether longitudinal or radial, such that that bipolar or unipolar radiofrequency energy may be transmitted between the electrodes to treat the tissue.
Because the treatment electrodes may be manipulated into a variety of different positions, adjacent electrodes may be unintentionally positioned too close to one another such that a short circuit may occur. For example, when the electrode array is torqued to define a substantially circular configuration, when a distal electrode in the array is torqued and manipulated toward a proximal electrode in the array to define a circle, depending on the skill of the surgeon, the array may be over-manipulated such that two or more electrodes may intermittently touch each other, or be positioned sufficiently close such that the flow of current between the electrodes shorts, resulting in treatment safety concerns.
Current methods of detecting short circuits in electrosurgical devices involve measuring impedance between the electrodes with a tissue to be treated sandwiched between them like a clamp, and measuring when the impedance rises above a predetermined value. When the impedance threshold is reached, the entire electrosurgical device is deactivated. However, such methods result in an all or nothing response to a short circuit and do not allow for deactivation of the particular shorted electrodes while keeping activated non-shorted electrodes. Further, because many different energy modes may be utilized during an RF ablation treatment, a single static impedance threshold value may be inaccurate for certain energy modes. Other methods include measuring the temperature at the electrodes and detecting a short between electrodes if the temperature of one of the electrodes exceeds a temperature threshold when the power is less than predetermined valve. This existing short circuit algorithm may detect excessive temperatures on the electrode during a short circuit, but does not always detect a short circuit when electrodes are close together since high temperatures normally occur between the electrodes.
Accordingly, what is needed is a method of a short-circuit detection that facilitates the on-off operation of individual electrodes in an electrode array that is specific to a particular energy delivery mode.